In the scope of the present invention, we mean by electrochemical device, a device which comprises:                at least one cell comprising a hydrogen electrode-electrolyte-oxygen electrode assembly,        at least two contact elements disposed on the hydrogen electrode and the oxygen electrode,        at least two interconnectors disposed on each of the contact elements.        
The interconnector is metallic and ensures the junction between two adjacent cells.
In a HTE-type electrochemical device, the water molecule is dissociated into dihydrogen at the hydrogen electrode (cathode), the O2− ions migrate through the electrolyte to recombine into dioxygen at the oxygen electrode (anode) side. Hence, the function of the cell is to produce dihydrogen by dissociating water molecules.
In a SOFC-type electrochemical device, oxygen is reduced at the oxygen electrode (cathode), the O2− ions migrate through the electrolyte to be oxidized by dihydrogen at the hydrogen electrode (anode). Hence, the function of the cell is to produce electricity by combining dihydrogen and dioxygen.
The interconnector conveys the current and distributes the gases (water vapor, dioxygen, dihydrogen, and possibly a carrier gas such as dinitrogen).
The contact element improves the electrical contact between the metallic interconnector and the electrode (namely the hydrogen electrode or the oxygen electrode).
An electrochemical device as described above is favored as a means for converting the chemical energy of a fuel into electrical energy if it is more effective than the other known means for converting the chemical energy into electrical energy.
The performance of such a chemical device is assessed by its effectiveness in producing electrical energy thanks to the electrochemical reactions implemented within the cell. This effectiveness is related to the quality of the electrical contacts established between the interconnectors and the electrodes, and this thanks to the contact elements.
Indeed, any ohmic loss in an electrochemical device is detrimental, because it contributes to decreasing its overall efficiency. In this regard, the ohmic losses are particularly significant and hence problematic in the case of electrochemical devices.
Therefore, it is sought to improve the quality of the electrical contacts between the interconnectors and the electrodes in order to increase the performances of these electrochemical devices.
In an electrochemical device, at the hydrogen electrode side, a nickel grid is conventionally used and it provides satisfactory results, and this at low costs.
But, the contact elements which ensure the passage of the current at the oxygen electrode side are currently the subject of numerous studies in order to improve their quality, and this while seeking for the lowest manufacturing costs.
It is known to use gold grids as contact elements at the oxygen electrode side. This material is soft and thus exhibits a good mechanical accommodation capacity, for example for:                filling the flatness defects,        smoothing a surface exhibiting a significant roughness of the electrode and/or the interconnector,        
Moreover, gold also has the advantage of being a good electrical conductor and having an excellent corrosion resistance.
Thus, the mechanical properties and the good electrical conductivity of gold allow obtaining a good electrical contact between the interconnector and the electrode and make the gold grid an appropriate embodiment as a contact element in an electrochemical device such as a SOFC or a HTE.
However, such a material has the drawback of being very expensive. Hence, it is not especially interesting, from an economic point of view, to use it as a contact element, due to the fact that it contributes to maintain high the production cost of an electrochemical device such as a SOFC or a HTE.
Therefore, other embodiments of contact elements, manufactured from more economically interesting materials, have been implemented. They consist of ceramic materials. But, these materials have the drawback of having a mechanical accommodation capacity which is not as effective as that of a gold grid.
Thus, to date, none of the embodiments of the contact elements known from the prior art is fully satisfactory to reconcile the following parameters:                a high conductivity;        a capacity of mechanical accommodation to the surface irregularities that the interconnectors and the electrodes may comprise;        a low cost of their constitutive materials for not impeding their use, for economic reasons, in electrochemical devices such as SOFCs and HTEs.        